Polymers have replaced metals glass, ceramics and papers in packaging, automobiles, building construction, electronics, electrical equipment, furniture, pipes and heavy industrial equipment. In a nutshell, from agriculture to transport and aerospace to food packaging, the use of plastics has become an integral part of our daily life. Polymers, all natural and synthetic, in common use, are susceptible to thermal/photo-oxidative degradation upon exposure to natural and artificial weathering. The deterioration of these polymeric materials is mainly due to the UV portion of sunlight reaching the earth surface. The net result of degradation is the loss in the molecular weight and macroscopic physical properties. In order to avoid this loss, different types of photo-stabilizers have been devised that protect the polymeric substrate from detrimental effect of light. Compatible and mobile light stabilizers usually prove to be best choice to attain the desired photostability. Most of these stabilizers are commercially available and are successfully employed, single and/or in combination with other stabilizers for the polymer stabilization. Researchers have even attempted to study the combined effect screeners, quenchers, ultraviolet absorbers and thermal stabilizers. An ample literature on the synthesis and application of these photostabilizers is available to date. Depending upon the type of combination, the effect of the stabilizers can be synergistic and antagonistic. The efficacy of the stabilizer depends on many factors viz, type of combination, proportion of additive, compatibility with the polymer and molecular weight of the stabilizer. Hindered amine light stabilizer (HALS) and benzotriazole based UV absorbers are known to work in synergism and there is no literature on the synthesis of the coupled derivatives of HALS and UV absorbers.
Keeping in view the above-mentioned requirements we have designed and synthesized a novel HALS coupled to an UV absorber. Following patents and literature provide information about synthesis of the photo-stabilizers and the photo-stabilization efficiencies of HALS and UV absorbers solely in presence of each other. JP 200119260: April 2000; U.S. Pat. No. 5977219: November 1999; JP 4263874 A2 September 1999; EP 924248 A1: June 1999; U.S. Pat. No. 5739348: April 1998; WO 9739052 A1: October 1997; U.S. Pat. No. 5362881 November 1994; U.S. Pat. No. 5086097 February 1994; Polym. Photochem, 5, 351 (1984), Polym, Degrad, Stab, 8, 133 (1984) and Polym Degrad. Stav. 32, 71 (1991). The process for the synthesis of compound having formula (II) has been disclosed in our co-pending patent application Ser. No. 09/749,277. An online search using SCIFINDER and CHEMICAL ABSTRACT search engines did not provide any positive result for any molecule similar to that synthesised in this invention.